Mechanical lesion generator



Nov. 6, 11962 n. A. KEATING 3,062,

MECHANICAL LESION GENERATOR Filed March 1, 1960 3 Sheets-Sheet 1 INVENTOR. DONALD A. KzA'rimi Nov. 6, 1962 D. A. KEATING 3,

MECHANICAL LESION GENERATOR Filed March 1. 1960 s Sheets-Sheet 2 INVENTOR. DONALD Fl. KEATI'NG Nov. 6, 1962 D. A. KEATING 3,

MECHANICAL LESION GENERATOR Filed March 1, 1960 3 Sheets-Sheet 3 Ila.

INVENTOR.

DONALD A. KEATING BY M FIZZ? ATTORNEYS United States Patent M 3,062,213 MECHANICAL LESION GENERATOR Donald A. Keating, 3235 White Oak Drive, Apt. 10, Dayton, Ohio Filed Mar. 1, 1960, Ser. No. 12,236 8 Claims. (Cl. 128303) This invention relates to a mechanical lesion generator for the neurosurgical alleviation of certain diseases having their origin or a means of control thereof, in the human brain; and more particularly a mechanical lesion generator especially adapted for the neurosurgical alleviation of Parkinsonism.

This application is a continuation-in-part of my copending application Serial No. 776,057 filed November 24, 195 8, now abandoned.

Parkinsons disease is one of the most baflling ailments of the 20th century, affecting more than 1,500,000 Americans. At the onset, the victim may feel a stiffness in his muscles. Normal walking and talking become increasingly difficult. He may sometimes shake uncontrollably. His movements become slow and unsure. He cannot form facial expression and finds it difficult to hold himself erect. As time progresses, so does the disease. The victim can no longer tie his shoelaces or button his coat, and the day comes when he must give up working. Eventually, the victim can no longer feed himself.

It has now been found that normal function can be restored or substantially improved in certain chronic diseases, particularly Parkinsons disease, by destroying normal brain tissue in certain specific areas. When injury to certain pathways in the brain has produced an unremitting disturbance in a patients control over movement, as in the tremor and rigidity of palsy or Parkinsonism, the writhing movements of athetosis, or the jerkings of choreic states, further destruction of what is termed the extra-pyramidal motor system in a confined anatomical area, the creation of lesions in the globus pallidus has been found to abolish dramatically the abnormal tone of certain muscles or the involuntary, jerky impulses to them, with great improvement in voluntary movement.

In certain states of intractable pain, resulting from injury or incurable cancer, the transmission of pain to conscious levels can be blocked by afferent pathways through small areas of destruction in the spinal cord or brain stem.

Accurate stereotaxic placement of a needle or fine plastic catheter so that its end will lie in a desired nucleus of the brain with no more than 2 mm. error in any coordinate is already entirely feasible. Properly projected X-ray studies of the head, after certain landmarks in the brain have been outlined with radio-opaque material injected into its arteries or its ventricles, allow calculation of the exact angle and depth to Which a needle must be inserted from its support on a calibrated frame afixed to the skull. The approach and arrival of the needle point at the proposed target is verified by additional serial X-rays. A route of approach can ordinarily be selected such that no tissue of important function is disturbed along the injection path. Reference may be had to Cooper, Irving 8.: The Neurosurgical Alleviation of Parkinsonism for the details of the operation for inserting a cannula into the brain and locating the globus pallidus by means of a pallidectomy guide- The technical problem of producing a localized sphere of brain destruction about the end of an inserted instrument has not been satisfactorily solved. Electrolytic lesions are satisfactory where the sphere of destruction is to be only one or two mm. in diameter. If the sphere must be 10 to mm. in diameter to produce the desired physiologic effect, the electrolytic technique becomes unwieldy 3,062,213 Patented Nov. 6, 1962 because of the necessity for multiple needlings and increased likelihood of chance damage to blood vessels en route. Even if this does not occur, a larger axis of intervening brain is damaged by multiple insertions. A second technique utilized is chemical in accordance with which the area of destruction about a needle point will be roughly proportionate to the volume of absolute alcohol injected (chemopallidectomy). However, the distribution of the injected material is capricious, being governed by chance tissue planes, so that destruction is often produced at a remote and undesirable point beyond the limits of the proposed sphere. There is a further possibility of chemical necrosis of small blood vessels which will lead to bleeding or thrombosis hours later, with far more destruction than was planned, and undesirable physiologic alteration.

A uniform needle incorporating at its point a plastic balloon capable of expansion so as to produce the desired sphere of destruction by gentle pressure has been previously attempted. However, these have the disadvantage of expanding eccentrically and unpredictably in relation to the volume of fluid injected. Quite frequently the plastic balloons break during the operation.

It is a principal object of this invention, therefore, to provide an instrument capable of yielding a controlled sphere of destruction. It has been found that such a controlled sphere of destruction may be accomplished by means of an instrument which expands a metallic band from its point with radii of controlled extent.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the appended claims, the following description and annexed drawing setting forth in detail certain illustrative embodiments of the invention, such disclosed means constituting, however, but a few of the various forms in which the principle of this invention may be employed.

Broadly stated, this invention is in the provision of a mechanical lesion generator for neurosurgical use comprising an outer tube and an inner tube telescopically assembled for relative movement, expansible band means anchored at one end of the inner tube to form a resilient loop portion projecting outwardly from the corresponding end of the outer tube, means for maintaining a predetermined axial dimension of the projecting portion of the loop, and means for moving the inner tube in either direction relative to the outer tube to selectively expand or contract the projecting portion of the loop.

In the annexed drawings:

FIG. 1 is a plan view of a mechanical lesion generator with accordance with this invention.

FIG. 2 is a fragmentary cross-sectional view of a means for advancing and retracting the inner tube to control the expansion and contraction of the expansible band.

FIG. 3 is a modification of the means shown in FIG. 2, additionally providing means for independent adjustment of the outer tube.

FIG. 4 is a fragmentary cross-sectional view of the expansible band end of the instrument.

FIG. 5 is an enlarged view of the end of the probe shown in FIG. 4.

FIG. 6 is a cross-sectional view taken on the line 66 of FIG. 4.

FIG. 7 is a fragmentary perspective view of the end of the outer tube.

FIG. 8 is a fragmentary perspective view of the end of the inner tube.

FIG. 9 is a fragmentary perspective view of the end of the probe tube.

FIG. 10 is a fragmentary side illustration of the distal end of inner tube 10 having a split band attached thereto composed of halves 2a.

FIG. 11 is an illustration of a different means for anchoring the bands to the probe tube.

' FIG. 12 is a fragmentary cross-sectional view of an assembled distal end of an instrument in accordance with this invention.

FIGS. 2 through 12 are shown in very much enlarged scale. V

' Referring more particularly to 'FIG. 1, there is here shown a full view of a mechanical lesion generator in accordance with this invention. instrument is composed of an outer tube -1 having an expansible band 2 protruding from one end thereof and having its other end attached to control means 3 for expanding and contracting the band 2. Piercing the entire instrument is a removable electrode probe 4. Manual control means 5, for example the knurled handled screw shank coacting with the housing 3, enables the surgeon to control the degree of expansion of the expansion band 2.

FIGS. 2 and 3 show in much enlarged detail a fragmentary cross-sectional view of a control means 3 suitable for use in accordance with this invention. FIGS. 2 and 3 also illustrate the additional function of the control means 3 for retaining the several tubular members. There is thus provided a housing 6 internally threaded as shown at 7, and fitted with a cover plate 8 at its one end. The cover plate 8 provides means for retaining the outer tube 1. As shown in FIG. 2, the outer tube 1 is soldered or otherwise rigidly afiixed to the cover plate 8. In FIG. 3, the outer tube 1 is movable with respect to the cover plate 8 as by a rack and pinion system 9 for advancing and retracting the outer tube 1 independently of the inner tube 14 Disposed within the inner tube 10 is a probe tube 11 which extends entirely through the, control means 3, the surgeons control and emerges at, the end of the instrument opposite the band end. Any suitable means 12 (FIG. 1) may be provided for securing the probe tube 11 to prevent axial displacement thereof. As shown in FIG. 1, this retaining means 12 is a pair of wire brackets, one end of which is soldered to the housing 6, and the other end of each of which is soldered to the probe tube 11.

As indicated above, the inner tube is telescopically assembled for relative movement with respect to both the probe tube 11 and the outer tube 1. The surgeons control 5" advances and retracts within the housing 6 as the surgeon may desire by rotating threaded surgeons control 5' in the desired direction. When thread means are em ployed for advancing and retracting the inner tube 10,

means must also be provided to prevent rotation of the inner tube 10 as the threaded control '5 revolves. Accordingly, in the embodiment shown in FIGS. 2 and 3, the threaded control 5 is provided with a cylindrical recess 13 and a cover plate 14 having a bore 15 therethrough so sized as to permit relative rotation of the cover plate 14 with respect to the inner tube 10. Mounted within the recess 13 is adisc 16 so sized as to permit relative rota- Generally speaking, the.

instrument and does not appear in FIG. 4. The band end of the probe provides an outer tube 1, an inner tube 10 telescopically assembled for relative movement within outer tube 1, and a probe tube 11. Probe tube 11 may be hollow and thus adapted to receive an electrode probe 4 as shown in FIG. 1 and FIGS. 5 and 6, or it may be solid. With the hollow tube, when the electrode 4 is withdrawn therefrom, the hollow tube may also be used for the purpose of injecting fluids. Also shown in FIG. 4 is the expansion band 2, which is aifixed to the outermost end of the probe tube 11 by suitable means at a point intermediate its ends. The free ends of the band 2 are then folded back on the probe tube 11 and aflixed to the telescopically movable inner tube 10. The probe tube 11 extends beyond the ends of both the outer tube 1 and the inner tube 10, and provides one means for maintaining a predetermined axial dimension of the projecting portion of the loop of band 2. The distance between the outer extremity of the probe tube 11 and the outer extremity of the outer tube 1 is set at a predetermined axial displacement. As shown in FIG. 3, adjusting means may be provided to vary the distance between the outer end of the probe tube 11 and the outer extremity of the outer tube 1. It will be observed that as the inner tube 10 is telescopically moved with respect to the outer tube 1 and the probe tube 11, the band 2 expands or contracts forming loops in a direction radial with respect to the probe tube 11.

FIG. 5 is an end view of the outer end of the probe shown in FIG. 4 with the exception that the electrode 4 is shown in place. The end of probe tube 11 may be notched as shown in FIG. 9 to receive the band 2 at a point intermediate its ends and hold the same firmly in place as by soldering. As shown in FIG. 5, the band 2 may be provided with an aperture 19 to permit the passage of the electrode 4 therethrough. Alternately, the band 2 may be soldered to the side of probe tube 11 and the notches 20' omitted, thereby avoiding the necessity of piercing the band 2.

In FIG. 6 there is shown in cross-section a view taken on the line 6-6 of FIG. 4. In this view the electrode 4 has been placed in position within the probe tube 11. FIG. 6 also shows the manner of attaching the free ends of the band 2 in the notched end of inner tube 10. Any suitable means for afiixing the ends of the band 2 in the notches 21 may be used such as imbedding in plastic, soldering, welding, etc.

' FIGS. 7, 8 and 9 are fragmentary prospective views of the outer ends of outer tube 1, inner tube 10 and probe tube 11, respectively, and show convenient notching of tion of the disc 16 within the recess 13 as the surgeons control 5 is rotated. The tube 10 is affixed by suitable means such as silver-soldering to the disc 16. The means for converting the rotatory and axial displacement of the threaded shank 5 to axial displacement only also includes a key 17 suitably afiixed to the inner tube 10 as by soldering, which key is adapted to traverse the slot 18 in the housing 6. Any other means for telescopically moving the inner tube 10 with respect to the outer tube 1 and the probe tube 11 without rotation of the inner tube 10 may, of course, be provided.

In FIG. 3, there is also shown means 9 foradjusting the position of the outer end of the outer tube- 1 with respect to the probe tube 11.

Referring more particularly to FIG. 4, this is a fragmentary cross-sectional view in enlarged size of the outer or band end of the structure shown in FIG. 1. The electrode. member 4 of FIG. 1 has been withdrawnfrom the the ends of these tubes to adapt them toreceive and guide the expansible band 2.

' It becomes convenient at this point to describe a specific and preferred embodiment of the present invention which is useful in the alleviation of Parkinsonism. When used for thispurpose, sizes of parts, especially the tubular parts and the expansion band, become extremely important and reference to actual sizes will be made, it being understood, however, that this specific example represents only one preferred embodiment of thepresent invention. Variations therein may be made by those skilled in the art without departing fromthe spirit of the invention.

The surgeons control 5, shown in FIGS. 1, 2 and 3, 1s the component part which the surgeon uses to control or govern the expansion of the lesion generating bands inside the brain. This part consists in the preferred form of a round shank, one end of which is a raised knurled portion for the surgeons touch control. For convenience, the shank portion has been identified in FIG. 1 as 22 and the raised knurled portion as 23. The other end of the surgeons control 5 is conveniently threaded such that the piston can screw'into thescrew housing 6. A drilled hole is provided throughout the. entire length of the surge'ons. control 5 to allow for passage of the probe tube therethrough to provide an entrance for the introductionof liquids such as'procaine or alcohol therethrough, or

E part is desirably made of brass to insure .a firm threaded portion. However, lighter materials such as aluminum may be used with advantage to reduce the moment force due to increased moment arm when this part is at its furthest extension out of the instrument. The total length of the screw travel in a preferred embodiment of this invention need not be more than 0.5 inch.

The internally threaded housing 6 is a cylindrical part with internal threads to receive the surgeons control and a keyway or slot 18 to guide the key 17. Only one end of the cylinder 6 is covered, in a preferred embodiment, and this is the end intermediate the extremities of the instrument and nearest the expansion band. The cover plate 8 is soldered to the end of the cylindrical housing 6 and provides the point of attachment of the outer tube 1. Brass is a preferred material for construction of the housing 6 because of its machineability and ability to be soldered. The cover plate 8 is desirably of the same material as the screw housing 6 (brass) so as to enable it to be easily soldered to the housing 6.

In a preferred embodiment of this invention, there is provided a part identified in FIGS. 2 and 3 as 16, which may, for convenience, be called the inner tube plate 16. The inner tube plate 16 is conveniently made of copper and has firmly affixed thereto, as by silver-soldering, the inner tube 10. The primary function of the inner tube plate 16, with the aid of the key 17, is to change combined rotary and axial motion of the surgeons control 5 into longitudinal, or axial motion only. The parts as shown in FIGS. 3 and 4 perform this function since the surgeons control 5 is free to rotate upon the inner tube plate 16 which is held captive within the recess 13 by the cover plate 1- Accordingly, there is imparted to the inner tube only longitudinal motion.

The key 17 is conveniently made of brass and has passing through it the inner tube 10 which is conveniently soldered to the key. The key 17 slides in the key way or slot 18 in the screw housing 5 which definitely insures longitudinal motion without any rotational motion derived from the surgeons control 5.

The plate 14 is also of brass with a drilled hole through it to allow complete freedom of its rotary motion upon the inner tube 10. It is soldered to the end of the surgeons control 5 and its sole function is to enclose and retain the inner tube plate 16 within the bore or recess 13, the bore therethrough being so sized as to fail to impart any rotary motion to the inner tube 10.

The physical dimensions of the portions of the instrument thus far described as comprising a preferred embodiment of the invention are not critical and need only be designed to accommodate the needs of the surgeon, hearing in mind the weight of the instrument, moment forces, etc. Thus the housing 6 may be 1.5 long by 0.5" diameter. The key-way 18 may be 0.75" long by 0.125 wide. The surgeous control 5 is 2.75" long with a threaded portion 0.75 long, 40 threads per inch, and 0.3125" pitch diameter. The recess 13 is 0.1875" diameter by 0.09375" deep. The shank portion is 0.25" diameter and the knurled portion 0.5" long by 0.625" diameter. The control 5' has an axial bore 0.032" in diameter. The cover plate 14 is 0.25 diameter by 0.0625" thick and has an axial bore 0.054" diameter. The inner tube plate 16 is 0.15625 diameter by 0.0625 thick with an axial bore 0.049 diameter. The key 17 is a brass block 0.125" x 0.125" x 0.310" with a bore 0.049" diameter on a central axis 0.0625" from base.

With the tubular portions of the preferred embodiment, more critical attention must be paid to the size of the tubes. The instrument, in one of its intended uses, is to be designed for insertion in the brain.

In the preferred embodiment, the outer tube 1 is desirably of standard AISZ Type 304 Austenitic chromiumnickel stainless steel hypodermic needle tubing. The tubing should be of hard-drawn temper which insures maximum hardness, and have a clean bright finish on both inside and outside surfaces so that the device can be easily sterilized. The outer tube 1 is the guiding tube for the inner tube 10. The outer tube 1 is fixed at one end to the cover plate 8. The other end is notched as shown in FIG. 7 so as to guide the band 2 in its expansion. The outer tube 1 and the probe end including the band 2 are in immediate contact with the brain. The opposite end of the tube near the surgeons control 5 will be clamped by a head cannula holder (not shown) so as to fix the instruments location in the brain according to procedures now well known to those skilled in the art.

The inner tube 10 desirably has the same metallurgical properties as the outer tube 1. One end of the tube 10 is fixed to the inner tube plate 16, and the outer end is desirably notched as shown in FIG. 8 and secured to the ends of the expansible band 2. The key 17 is also fixed to this tube 10 to insure only longitudinal motion. This tube 10 can be considered to be a link between the surgeons control 5 and the band 2.

The probe tube 11 desirably has the same metallurgical properties as the outer tube 1 and the inner tube 10. The band end of the tube 11 is notched as shown in FIG. 9 and secured to the band 2 so as to fix its location. The probe tube 11 is the longest tube in the instrument and in the preferred embodiment extends the entire length so that its extremity opposite to the band end may be secured as by retaining arms 12 (FIG. 1) to prevent axial displacement thereof with respect to the outer tube 1. In a preferred embodiment of this invention, the distance between the ends of the outer tube 1 and the probe tube 11 is 5 mm. As shown in FIG. 3, the distance between the ends of the outer tube 1 and the probe tube 11 may be made adjustable so that a range of axial displacement of the relative ends of outer tube 1 and probe tube 11 may vary from about 4 to about 15 mm. Alternatively, the outer tube 1 may be fixed as in FIG. 2 and the probe tube 11 made adjustable as by a set screw in the wire bracket 12, not shown. The probe tube 11 itself extends back through the instrument so as to be a guide for the electrode probe 4 and when the electrode probe 4 is withdrawn from the instrument to serve as a channel for the introduction of liquid medicaments.

As indicated above, the size of these tubes is somewhat critical. The following internal and external diameters of tubes suitable for use in accordance with this invention are dictated by commercially available tube sizes and are offered as a guide to the magnitude of tubes which may be used for neurosurgical operation purposes. Variations from these sizes are, of course, possible but should be designed within the limits dictated bythe physiological effect of such tube on the membrane or organ wherein it is to be used.

The outer tube, therefore, in a preferred embodiment has an OD. of 0.072 inch and an ID. of 0.054 inch. The inner tube has an 0.1). of 0.049 inch and an ID. of 0.033 inch. The probe tube has an CD. of 0.032 inch and an ID. of 0.020 inch. The dimensions of the notching in each of the tubes is conveniently as follows: On the outer tube the notch is conveniently 0.025 inch wide and 0.010 inch deep (axial). On the inner tube, the notch is conveniently 0.015 inch wide and 0.1875 inch long. On the probe tube, the notch is conveniently 0.015 inch wide and 0.010 inch deep. Where an electrode tube is used, it may have an 0.1). of 0.018 and an ID. of 0.010 inch.

The length of the respective tubes will, of course, be determined by convenience in design. In the device not providing for adjustable distance between the ends of the outer tube 1 and the probe tube 11, a convenient distance (fixed) between such ends is 5 mm. In such a fixed device, the outer tube may conveniently have a length of 5.06 inch, the inner tube a length of 5.50 inches and the probe tube a length of 9.0 inches.

The expansion band is perhaps the most important part of the instrument as its purpose is to generate the desired.

lesion by gentle pressure upon that portion of the brain to bedamaged. The expansion band 2 is a continuous band of flat Invar-alloy clock spring strip 0.008 inch thick, 0.020 inch in width, and 1.50 inches long. The ends of this band are silver-soldered to the inner tube 10 and at a point intermediate its ends to the probe tube end. The band 2 is expanded by longitudinal motion of the inner tube 10,- thus buckling or expanding the band.- At full expansion, the path of lesion will be elliptical in shape,,being 5 mm. at the minor axis and about mm. at the major axis. A very thin coating of polyethylene may be applied to the band. The coating is inert and will produce no chemical reaction in. the brain. Further the coating acts as a safety feature if the metal band should fracture. The expansion can then be contracted without rupture of the coating by the metal band which would induce laceration of brain tissue. The coating also serves to round the sharp corners of the rectangular spring strip and will insure against laceration of brain tissue and vessels. Polyethylene can be coated on the metal by dipping or flame spraying. The best material which has been found for making the expansible band 2 is Invar-clock spring alloy. material expanding to a loop having its base 5 mm. long, can withstand a maximum deflection radially of about 0.438 inch before the band will flop over. and form a closed loop. This is more than sufiicient for the purposes of the present invention since the maximum radial expanion on a base 5 mm. in length will be no more than about 10 mm. Stainless spring steel maybe used since it satisfies the requirement of a maximum deflection (y greater than 2.5 mm., the material is relatively inert and is currently used in surgery. It is capable of being easily soldered to the inner tube. However, stainless steel spring wire thinner than 0.005 inch in diameter is seldom made. Linear polyethylene also satisfies the (y requirement of 2.5 mm. or greater. However, at expansion it is extremely flexible and giveslittle resistance to any applied pressure. It is also difficult to secure apolyethylene. band to the inner tube 10. While polyethylene is not a preferred material for use in designing the band, it is very useful as a band covering. Clock.

spring steel, S.A.E. 1095 is not recommended since its (y is not that of 2.5 mm. or greater. The theoretical calculation was checked by experiment which demonstrated fracture of the band at 2.5 mm. expansion. The Invar-alloy is an alloy of nickel and exhibits the properties of high strength, low modulus of elasticity and resistance to many chemicals and corrosion. The maxi mum deflection at expansion can be made greater than 5 mm at which the band oifers considerable resistance to applied pressure at its surface. The band can be silver-soldered to the inner tube 10 and the end of probe tube 11 without any bonding problems. The band can be expanded Without any fatigue problems if (y is never greater than 5 mm., such that the band is not in the plastic range undergoing cold working. This material possesses all of the requirements and is easily obtained, and can be coated with polyethylene. This material is a preferred material for the expansion band. Any suitable means of attaching the band, or halves thereof, to the probe tube and the inner tube may be employed.

Further in accordance with this invention, I have provided the structure shown in FIGS. l0, l1 and 12 as a means for anchoring a divided band 2. to the distal end of the instrument.

FIG. 10 shows a fragmentary side illustration of the distal end of the inner tube 10 having a split band 2 composed of halves 2a and 2a.v The free ends of the bands 2a are conveniently provided with loops 24 adapted to loosely encircle'an axle member 23 (FIG. 11). The axle member 23 is illustrated in FIG. 11 as a metallic ring 23 afiixed to a. slotted sleeve 22 which tightly fits over the :It has been found that this.

distal extremity of probe tube 11a. Axle pins spanning the slots 25 might also be used for anchoring means or hinges for the divided band sections 2a.

FIG. 12 is a fragmentary cross-sectional view of an assembled distal end of an instrument in accordance with this invention embodying the structure utilizing a divided band 2, and illustrating a preferred means for anchoring sections 2a. The outer tube 1 is partially shown with inner tube 10 telescopically moveably retained therein. Band portions 2a, 2a are fixedly attached to inner tube 20 as by silver soldering. Probe tube 11a is shown in place having the sleeve 22 fitted over its extremity. The loops 24 encircle the ring 23 and are restrained from lateral movement by portions of the loops 24 resting in slots 25, respectively. Probe tube 11a is modified to eliminate notches 20 in probe tube 11 (FIG. 9) and adapt it to receive and retain sleeve 22.

In making the soldered joints, consideration should be given to sterilization temperatures. Silver-soldering is satisfactory for either autoclaving or chemical sterilization techniques. To maintain the metallurgical properties of the band, gas or cold sterilization is preferred.

In the surgical operation, the instrument is placed in a cannula guide and enters the brain only a short distance. The electrode probe 4 is then advanced farther into the brain. With proper recording and measuring equipment in use, the electrode is advanced until the lesion site is located. The electrode probe is now clamped in position by an extension of the cannula holder. The instrument itself is now advanced until it is at the site of future destruction within 2 mm. error. by X-ray. Once the instrument is at the lesion site, itv is clamped into a fixed location by the cannula holder. The electrode-probe is then withdrawn. Now approximately 0.25 cubic centimeter of procaine is injected into the brain through the probe tube 11. If localization has been accurate, this injection of procaine will result in an immediate marked lessening or abolition of contra-lateral. tremor and rigidity. If it does not, the needle is advanced to a greater depth and injection is repeated. If. neither of these localizations produce alleviation of tremor and rigidity, one must replace the needle in a more anterior or a more posterior plane, depending to a large extent on past surgical experience.

Once procaine injection has resulted in alleviation of contralateral tremor and rigidity, one can then proceed with the production of a destructive lesion. The lesionis generated by simply turning the surgeons control 5 which displaces the inner tube 10 longitudinally, thus expanding the band 2 in one plane. Throughoilt the period of expansion, one tests the contralateral extremities as well as speech and mental functions, the patient being under only local anesthesia during the operation. If any untowards signs or symptoms develop during expansion, one can terminate the procedure without enlarging the lesion. The expansion is continued until the desired results are obtained, or until the limit of the instrument is reached. The surgeon can then collapse the band and rotate the instrument in another plane, thus generating the lesions in more than one plane, if he so wishes or deems it more beneficial. The operation can then be completed by simply collapsing the band 2 and withdrawing the instrument from the brain.

Other modes of applying the principle of this invention may be employed instead of those specifically set forth above, changes being made as regards the details herein disclosed, provided the elements set forth in any of the following claims, or the equivalent of such be employed.

It is, therefore, particularly pointed out and distinctly claimed as the invention:

1. A mechanical lesion generator for neurosurgical use comprising an outer tube and an inner tube telescopically assembled for relative movement, and a probe member disposed within said inner tube, said probe member ex.- tending beyond the extremity of said inner tube, expan- The location is checked.

sible band means anchored at one end of the inner tube and to the outer end of said probe member to form a resilient loop portion projecting outwardly from the corresponding end of said outer tube, means for maintaining a predetermined fixed axial dimension of the projecting portion of the loop between the distal end of said probe member and the distal end of said outer tube, and means for moving the inner tube in either direction relative to the outer tube to selectively expand or contract the projecting portion of the loop.

2. A mechanical lesion generator for neurosurgical use comprising an outer tube, an inner tube concentrically disposed within said outer tube, and a probe member disposed within said inner tube, said probe member extending beyond the extremity of said inner tube, an expansible band secured at a point intermediate its ends to the outer end of said probe member, and said band having its extremities secured to the end of said inner tube adjacent said outer end of said probe member, means for maintaining a predetermined fixed axial dimension of the projecting portion of the loop between the distal end of said probe tube and the distal end of said outer tube, and means for telescopically moving said inner tube relative to said probe member and said outer tube to expand and contract said band.

3. A mechanical lesion generator for neurosurgical use comprising an outer tube and an inner tube telescopically assembled for relative movement, and a probe member disposed within said inner tube, said probe member extending beyond the extremity of said inner tube, expansible band means including a pair of flexible bands disposed on opposite sides of said probe member each of said bands being anchored at one end of said inner tube, and the other end hinged to the outer end of said probe member to form a pair of resilient loops projecting outwardly from the corresponding end of the outer tube, means for maintaining a predetermined fixed axial dimension of the projecting portions of the loops between the distal end of said probe tube and the distal end of said inner tube, and means for moving the inner tube in either direction relative to the outer tube to selectively expand or contract the projecting portion of the loops.

4. The mechanical lesion generator of claim 3 wherein the probe member is tubular.

5. A mechanical lesion generator for neurosurgical use comprising an outer tube, an inner tube concentrically disposed within said outer tube, and a probe member disposed Within said inner tube, said probe member extending beyond the outer extremities of said inner tube and said outer tube, means for adjusting and fixing the distance between the outer extremity of said probe member and the outer extremity of said outer tube, an expansible band secured at a point intermediate its ends to the outer extremity of said probe member and said band having its extremities secured to the outer extremity of said inner tube, and means for telescopically moving said inner tube independently of said probe member and said outer tube to expand said band to form substantially U-shaped loops of said band projecting laterally from said probe member and to contract said band inwardly toward said probe member.

6. A mechanical lesion generator for neurosurgical use comprising an outer tube, an inner tube concentrically disposed within said outer tube, and a tubular probe member concentrically disposed within said inner tube and extending beyond the extremities of said outer tube and means for fixing the axial relationship of said inner tube, said outer tube and said probe member, an ex- 10 pansible band secured at a point intermediate its ends to the outer extremity of said probe member, and said band having its extremities secured to the end of said inner tube adjacent said outer extremity of said probe member, and means for telescopically moving the said end of said inner tube in either direction in the annular space between said probe member and said outer tube to expand and contract said band.

7. A mechanical lesion generator for neurosurgical use comprising an outer tube, an inner tube concentrically disposed Within said outer tube, and a tubular probe member concentrically disposed Within said inner tube and extending beyond the extremities of said outer tube and means for fixing the axial relationship of said inner tube, said outer tube and said probe member, an expansible band secured at a point intermediate its ends to the outer extremity of said probe member, and said band having its extremities secured to the end of said inner tube adjacent said outer extremity of said probe member, and means for telescopically moving the said end of said inner tube in either direction in the annular space between said probe member and said outer tube to expand and contract said band, a housing provided at one end with an apertured plate for passing said inner tube and said probe member therethrough, said plate fixedly retaining said outer tube, a piston within said housing mounted for axial movement in either direction within said housing and having said inner tube attached thereto, means for moving said piston in either direction independently of said probe member, means coacting with said inner tube to prevent rotation thereof about its axis, and means for anchoring said probe member to said housing.

8. A mechanical lesion generator for neurosurgical use comprising an outer tube, an inner tube concentrically disposed within said outer tube, and a tubular probe member concentrically disposed within said inner tube and extending beyond the extremities of said outer tube and said inner tube, said outer tube and said probe member being in fixed axial relationship, an expansible band secured at a point intermediate its ends to the outer extremity of said probe member, and said band having its extremities secured to the end of said inner tube adjacent said outer extremity of said probe member, and means for telescopically moving the said end of said inner tube in either direction in the annular space between said probe member and said outer tube to expand and contract said band, an internally threaded cylinder provided at its innermost end with an apertured plate for passing said inner tube and said probe therethrough, said plate fixedly retaining said outer tube, a threaded piston within said cylinder mounted for axial movement in either direction within said cylinder, means for converting the rotatory and axial displacements of said threaded piston to axial displacement only and transmitting said axial displacement to said inner tube, said threaded piston having a bore for passing said probe member therethrough, and means for anchoring said probe member to said cylinder to restrain axial movement thereof.

References Cited in the file of this patent UNITED STATES PATENTS 618,521 Palmer Jan. 31, 1899 654,763 Russell July 31, 1900 687,112 Bowker Nov. 19, 1901 1,677,209 Rose July 17, 1928 

